Moscow is claiming the charges against 13 Russian nationals and three Russian companies for meddling in the 2016 U.S. election are "blather."

Speaking at the Munich Security Conference in Germany, where dozens of world leaders are gathered this weekend, Russian Foreign Minister Sergey Lavrov on Saturday questioned the evidence presented by the U.S. Justice Department and special counsel Robert Mueller.

"You know I have no reaction at all, because one can publish whatever one wants," he said. "We see how accusations, statements, allegations multiply. Until we see the facts, everything else is just blather. I beg your pardon for a not really diplomatic wording."

Mueller's investigation has shed further light on Russia's efforts to influence U.S. politics in cyberspace. The indictments suggest that a Russian propaganda arm oversaw a criminal and espionage conspiracy to influence the 2016 presidential campaign, by supporting Donald Trump and disparaging his rival, Hillary Clinton.

The indictments have created added tension at the three-day gathering of global political and military leaders in Munich.

Lavrov's appearance at the podium Saturday was followed immediately by that of White House national security adviser H. R. McMaster, whose response also was blunt.

"The United States will expose and act against those who use cyberspace, social media and other means to advance campaigns of disinformation, subversion and espionage," he told delegates.

McMaster said the United States would support Russia's proposition of a cybersecurity dialogue, but only when Moscow is sincere about curtailing its interference in Western democracies.

Effort seen backfiring

"What's happened is in this effort to polarize our societies — to support rightist groups, even the most extreme forms of fascist groups, and then groups on the left, in an attempt to pit Western societies against each other — all that has done is appeal to those big fringes while uniting all of our polities actually against Russia," McMaster said.

WATCH: National Security Advisor H.R. McMaster's speech in Munich

Former U.S. Vice President Joe Biden, also in Munich, said the West must counter Russian interference. "[Russian President Vladimir] Putin has to know the cost of this behavior in the long run will certainly outweigh the benefit" now perceived, he said.

Russian representatives in Munich have sought to present the claims of interference in Western democracies as part of a coordinated campaign of "Russophobia."

In Russia, news of the indictments was met with more scorn.

"There are no official claims, there are no proofs for this. That's why they are just children's statements," Andrei Kutskikh, the presidential envoy for international information security, told Russian state news agency RIA Novosti.

A view of the four-story building known as the "troll factory" in St. Petersburg, Russia, Feb. 17, 2018. The U.S. government alleges the Internet Research Agency started interfering as early as 2014 in U.S. politics, extending to the 2016 presidential election, saying the agency was funded by a St. Petersburg businessman, Yevgeny Prigozhin.

One of the 13 people indicted said that the U.S. justice system was unfair.

Mikhail Burchik was quoted Saturday by the newspaper Komsomolskaya Pravda as saying that "I am very surprised that, in the opinion of the Washington court, several Russian people interfered in the elections in the United States. I do not know how the Americans came to this decision."

Burchik was identified in the indictment as executive director of an organization that allegedly sowed propaganda on social media to try to interfere with the 2016 election.

He was quoted as saying that "they have one-sided justice, and it turns out that you can hang the blame on anyone."

But Moscow is struggling to defend itself in the face of overwhelming evidence, according to Ben Nimmo of the Atlantic Council's Digital Forensic Research Lab, a specialist in cyber- and hybrid warfare.

'Absolutely damning'

"The fact is that now we have independent Russian media that have named the troll factory accounts; Facebook and Twitter have confirmed the troll factory accounts on Facebook and Twitter. That is absolutely damning," Nimmo said. "There is no possible way you can say that that didn't happen. You now have the Department of Justice further confirming it."

U.S. officials say Mueller's investigation into Russian meddling is not finished. The White House maintains the indictments show there was no collusion between the Donald Trump presidential campaign team and Russian intelligence.